TW202334551A - Cryopump and method for driving cryopump - Google Patents

Abstract

A cryopump (10) is attachable to a vacuum chamber through a gate valve (102). The cryopump (10) is provided with a refrigerator (14), and a controller (60) that is configured to detect whether or not the gate valve (102) is closed, and to control the refrigerator (14) to increase the refrigeration capacity of the refrigerator (14) when the gate valve (102) is closed, in comparison to when the gate valve (102) is opened.

Description

Cryopump and how to operate the cryopump

The present invention relates to a cryogenic pump and an operating method of the cryogenic pump.

A cryopump is a vacuum pump that captures gas molecules on a cryogenic plate that is cooled to extremely low temperatures through condensation or adsorption and exhausts them. Cryogenic pumps are generally used to achieve a clean vacuum environment required in semiconductor circuit manufacturing processes and other processes. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2012-237293

[Problem to be solved by the invention]

In order to fully increase the vacuum degree of the vacuum chamber as preparation for starting the vacuum process in the vacuum chamber of the vacuum process device, the vacuum chamber is first roughly evacuated, and then switched to vacuum exhaust based on a cryopump. When rough evacuation of the vacuum chamber is performed, the gate valve provided between the vacuum chamber and the cryopump is closed, and the gate valve is opened in order to start vacuum evacuation by the cryopump. At this time, the reaching pressure in the cryopump is much lower than the rough pumping pressure of the vacuum chamber. Therefore, a large amount of gas flows from the vacuum chamber into the cryopump at one time, which becomes a heat load on the freezer that cools the cryopump, and may cause the cryopanel temperature to overshoot. This temperature rise is also called crossover. The temperature rise of the cryopanel may adversely affect the exhaust performance of the cryopump in some cases.

In addition, as a unique setting in the vacuum sequencer, the allowable range of the cryopanel temperature may be set in advance. If it is detected that the above-mentioned overshoot result exceeds the allowable temperature range, it is possible to perform actions to ensure safety by issuing an alarm or emergency closing of the gate valve through the vacuum program device. The vacuum program device is on standby until the cryopanel temperature returns to the allowable range, and the start of the vacuum program is delayed accordingly.

One of the exemplary purposes of an embodiment of the present invention is to provide a cryopump capable of mitigating overshoot of the cryopanel temperature that may occur during a crossover. [Technical means to solve problems]

According to an implementation aspect of the present invention, a cryogenic pump that can be installed in a vacuum chamber via a gate valve is provided. The cryopump includes: a refrigerator; and a controller configured to detect whether the gate valve is closed and control the refrigerator so that the freezing capacity of the refrigerator when the gate valve is closed is greater than when the gate valve is open.

According to an implementation aspect of the present invention, a method for operating a cryogenic pump is provided. The cryopump can be installed in the vacuum chamber via a gate valve and equipped with a freezer. The method includes the following steps: detecting whether the gate valve is closed; and increasing the freezing capacity of the refrigerator when the gate valve is closed compared to when the gate valve is open.

According to an implementation aspect of the present invention, the cryopump includes: a refrigerator; and a controller that detects whether the regeneration of the cryopump is completed and controls the refrigerator to temporarily increase the freezing capacity of the refrigerator after the regeneration is completed.

According to an implementation aspect of the present invention, a method for operating a cryogenic pump is provided. The cryopump has a freezer. The method includes the following steps: detecting whether the regeneration of the cryopump is completed; and temporarily increasing the freezing capacity of the freezer after the regeneration is completed.

Furthermore, any combination of the above constituent elements or the mutual replacement of the constituent elements or expressions of the present invention between methods, devices, systems, etc. are also effective as implementation aspects of the present invention. [Effects of the invention]

According to the present invention, it is possible to provide a cryopump capable of mitigating an overshoot of the cryopanel temperature that may occur at the time of crossover.

Hereinafter, the mode for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are denoted by the same component signs, and repeated descriptions are appropriately omitted. The scale and shape of each part shown in the figures are simply set for convenience of explanation, and are not to be interpreted restrictively unless otherwise specified. The embodiments are examples and do not limit the scope of the present invention in any way. All features described in the embodiments or combinations thereof are not necessarily essential to the invention.

FIG. 1 is a diagram schematically showing a cryopump 10 according to the embodiment. FIG. 2 is a block diagram schematically showing the structure of the control device of the cryopump 10 according to the embodiment.

For example, the cryopump 10 can be installed in the vacuum chamber 100 of an ion implantation device, a sputtering device, an evaporation device, or other vacuum processing devices via a gate valve 102 . In FIG. 1 , part of the vacuum chamber 100 and the gate valve 102 are shown together with the cryopump 10 .

The cryopump 10 is installed in the vacuum chamber 100 via the gate valve 102 to increase the vacuum degree inside the vacuum chamber 100 to a level required by a desired vacuum procedure. The cryopump 10 has a cryopump suction port (hereinafter also referred to as "suction port") 12 for receiving gas to be exhausted from the vacuum chamber 100 . The gas enters the internal space of the cryopump 10 from the vacuum chamber 100 through the gate valve 102 and the suction port 12 .

In addition, in the following, in order to express the positional relationship of the components of the cryopump 10 in an easy-to-understand manner, the terms "axial direction" and "radial direction" may be used. The axial direction of the cryopump 10 represents the direction passing through the suction port 12 (that is, the direction along the central axis of the cryopump 10, which is the up and down direction in the figure), and the radial direction represents the direction along the suction port 12 (which is the direction along the suction port 12). The direction perpendicular to the central axis of the cryopump 10 is the left-right direction in the figure). For convenience of explanation, the position relatively close to the suction port 12 in the axial direction may be called "upper" and the position relatively far away from the suction port 12 may be called "lower". That is, a position relatively far from the bottom of the cryopump 10 may be called "upper" and a position relatively close to the bottom of the cryopump 10 may be called "lower". Regarding the radial direction, the position close to the center of the suction port 12 may be called "inside" and the position close to the periphery of the suction port 12 may be called "outer". Furthermore, such expression has nothing to do with the configuration when the cryopump 10 is installed in the vacuum chamber 100 . For example, the cryopump 10 may be installed in the vacuum chamber 100 so that the suction port 12 faces downward in the vertical direction.

Also, the direction surrounding the axial direction may be called "circumferential direction". The circumferential direction is the second direction along the suction port 12 and is a tangential direction orthogonal to the radial direction.

The cryopump 10 includes a refrigerator 14, a cryopump container 16, a first-stage cryopanel 18, and a cryopanel unit 20. The first stage cryopanel 18 can also be called a high-temperature cryopanel part or a 100K part. The cryopanel unit 20 is a second-stage cryopanel, and may also be called a low-temperature cryopanel section, a 10K section, or the like.

The refrigerator 14 is, for example, a very low temperature refrigerator such as a Gifford-McMahon refrigerator (so-called GM refrigerator). The refrigerator 14 is a two-stage refrigerator and includes a first cooling stage 22 and a second cooling stage 24 . The refrigerator 14 is configured to cool the first cooling stage 22 to the first cooling temperature and to cool the second cooling stage 24 to the second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling stage 22 is cooled to about 60K to 120K, preferably 80K to 100K, and the second cooling stage 24 is cooled to about 10K to 20K. The first cooling stage 22 and the second cooling stage 24 may also be called a high temperature cooling stage and a low temperature cooling stage respectively.

Moreover, the refrigerator 14 is provided with the refrigerator structural part 21. The refrigerator structural part 21 structurally supports the 2nd cooling stage 24 by the 1st cooling stage 22, and the 1st cooling stage 22 is structurally supported by the room temperature of the refrigerator 14. Part 26 supports. Therefore, the refrigerator structural part 21 includes the first cylinder 23 and the second cylinder 25 that extend coaxially in the radial direction. The first cylinder 23 connects the room temperature part 26 of the refrigerator 14 and the first cooling stage 22 . The second cylinder 25 connects the first cooling stage 22 and the second cooling stage 24 . Typically, the first cooling stage 22 and the second cooling stage 24 are formed of a highly thermally conductive metal material such as copper (for example, pure copper), and the first cylinder 23 and the second cylinder 25 are formed of other metal materials such as stainless steel. The room temperature part 26, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are linearly arranged in order.

A first displacer and a second displacer (not shown) are disposed in each of the first cylinder 23 and the second cylinder 25 so as to be reciprocally movable. A first regenerator and a second regenerator (not shown) are respectively assembled to the first displacer and the second displacer. Moreover, the room temperature part 26 has a drive mechanism (not shown) for reciprocating the 1st displacer and the 2nd displacer. The drive mechanism includes a refrigerator motor 50 described below. Furthermore, the driving mechanism includes a flow path switching mechanism that switches the flow path of the working gas (for example, helium gas) inside the refrigerator 14 so as to periodically repeat the supply and discharge of the working gas.

The refrigerator 14 is connected to a working gas compressor (not shown). The refrigerator 14 cools the first cooling stage 22 and the second cooling stage 24 by internally expanding the working gas pressurized by the compressor. The expanded working gas is recovered by the compressor and pressurized again. The refrigerator 14 performs refrigeration by repeatedly performing a thermal cycle including supply and discharge of working gas and reciprocating movement of the first displacer and the second displacer in synchronization with this.

The cryopump 10 shown in the figure is a so-called horizontal cryopump. The horizontal cryopump is usually a cryopump arranged so that the central axes of the refrigerator 14 and the cryopump 10 intersect (usually orthogonally). Furthermore, the present invention can be similarly applied to a so-called vertical cryopump. The vertical cryopump is a cryopump that is installed along the axial direction of the cryopump in the freezer.

The cryopump container 16 is a casing of the cryopump 10 that accommodates the refrigerator 14, the first-stage cryopanel 18, and the cryopanel unit 20, and is configured to maintain airtightness of the internal space of the cryopump 10. The cryopump container 16 has a suction port flange 16a extending radially outward over the entire circumference from its front end. The suction port 12 is defined radially inwardly by the suction port flange 16a. Furthermore, the cryopump container 16 has a container body 16b extending in the axial direction from the suction port flange 16a; a container bottom 16c closing the container body 16b on the side opposite to the suction port 12; and a refrigerator storage tube 16d. Extends laterally between the suction port flange 16a and the container bottom 16c.

The end portion of the refrigerator storage tube 16d is attached to the room temperature portion 26 of the refrigerator 14 on the side opposite to the container body 16b, whereby the low-temperature portion of the refrigerator 14 (that is, the first cylinder 23, the first The cooling stage 22 , the second cylinder 25 and the second cooling stage 24 ) are arranged in the cryopump container 16 in a non-contact manner with the cryopump container 16 . The first cylinder 23 is arranged in the refrigerator storage tube 16d, and the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are arranged in the container body 16b. The first stage cryopanel 18 and the cryopanel unit 20 are also arranged in the container body 16b.

The first stage cryopanel 18 includes a radiation shield 30 and an inlet cryopanel 32 and surrounds the cryopanel unit 20 . The first stage cryopanel 18 provides an extremely low temperature surface for protecting the cryopanel unit 20 from radiant heat from the outside of the cryopump 10 or from the cryopump container 16 . The first stage cryopanel 18 is thermally coupled to the first cooling stage 22 and is cooled to the first cooling temperature. There is a gap between the first stage cryopanel 18 and the cryopanel unit 20 , and the first stage cryopanel 18 is not in contact with the cryopanel unit 20 . The first stage cryopanel 18 is also not in contact with the cryopump container 16 .

The radiation shield 30 is provided to protect the cryopanel unit 20 from radiant heat of the cryopump container 16 . The radiation shield 30 extends in the cryopump container 16 in an axial direction from the suction port 12 toward the container bottom 16 c in a tubular shape (for example, a cylindrical shape). The radiation shield 30 is open on the suction port 12 side and closed on the container bottom 16c side. Radiation shield 30 is located between cryopump container 16 and cryopanel unit 20 and surrounds cryopanel unit 20 . The radiation shield 30 has a slightly smaller diameter than the cryopump container 16 , and a shield outside gap 31 is formed between the radiation shield 30 and the cryopump container 16 . Therefore, the radiation shield 30 is not in contact with the cryopump container 16 .

The first cooling stage 22 of the refrigerator 14 is directly mounted on the outer side surface of the radiation shield 30 . In this way, the radiation shield 30 is thermally coupled to the first cooling stage 22 and is therefore cooled to the first cooling temperature. Furthermore, the radiation shield 30 can also be installed on the first cooling stage 22 via an appropriate thermal conductive member. Furthermore, the second cooling stage 24 and the second cylinder 25 of the refrigerator 14 are inserted into the radiation shield 30 from the side of the radiation shield 30 .

In order to protect the cryopanel unit 20 from radiant heat from an external heat source of the cryopump 10 (for example, a heat source in a vacuum chamber in which the cryopump 10 is installed), an inlet cryopanel 32 is provided on the suction port 12 . The inlet cryopanel 32 is thermally coupled to the first cooling stage 22 via the radiation shield 30 and is cooled to the first cooling temperature in the same manner as the radiation shield 30 . Therefore, gas (for example, moisture) condensed at the first cooling temperature is trapped on its surface.

The cryopanel unit 20 includes a plurality of cryopanels, each of which is thermally coupled to the second cooling stage 24 and cooled to a second cooling temperature lower than the first cooling temperature. As shown in the figure, the cryopanels may be arranged axially from the suction port 12 toward the bottom 16c of the container. An adsorbent material (eg, activated carbon) may be disposed on at least a portion of the surface of the cryopanel to capture non-condensable gas (eg, hydrogen) by adsorption. The cryopanel unit 20 is arranged below the inlet cryopanel 32 so as to be surrounded by the radiation shield 30 in the cryopump container 16 . The cryopanel unit 20 is not in contact with the radiation shield 30 and the inlet cryopanel 32 . In addition, as for the structure of the cryopanel unit 20 such as the arrangement and shape of the cryopanel, various well-known structures can be appropriately adopted, and therefore detailed description is omitted here.

The gate valve 102 is provided between the cryopump 10 and the vacuum chamber 100 . The gate valve 102 includes a valve housing 104 and a valve plate 106 . The valve housing 104 forms a communication passage that connects the opening of the vacuum chamber 100 and the suction port 12 of the cryopump 10 . The valve housing 104 has flanges on both sides of the communication passage. The flange on one side is mounted on the flange of the vacuum chamber 100 surrounding the opening of the vacuum chamber 100 , and the flange on the opposite side The part is installed on the suction port flange 16a.

The gate valve 102 is closed as necessary when performing maintenance on the vacuum chamber 100 or the cryopump 10 . The flange portion on the suction port flange 16a side of the valve housing 104 also functions as a valve seat portion of the gate valve 102, and the valve plate 106 as the valve body is brought into close contact with the valve seat portion, thereby closing the gate valve 102. At this time, the gas flow from the vacuum chamber 100 to the cryopump 10 through the suction port 12 is blocked. The cryopump 10 is isolated from the vacuum chamber 100, and the internal space of the cryopump 10 remains airtight.

The gate valve 102 is opened to perform vacuum evacuation of the vacuum chamber 100 by the cryopump 10 . The valve housing 104 is provided with a valve plate receiving portion 108. As shown by a dotted chain line in FIG. 1, when the valve plate 106 leaves the valve seat portion of the valve housing 104 and is received in the valve plate receiving portion 108, the gate valve 102 Open. Gas can enter the internal space of the cryopump 10 from the vacuum chamber 100 through the gate valve 102 and the suction port 12 . In this way, in order to perform a desired vacuum process in the vacuum chamber 100 , the vacuum chamber 100 can be evacuated by the cryopump 10 .

As shown in FIG. 2 , the cryopump 10 may include: a first temperature sensor 40 for measuring the temperature of the first cooling stage 22 ; and a second temperature sensor 42 for measuring the temperature of the second cooling stage 24 . The first temperature sensor 40 is installed on the first cooling stage 22 or the first stage cryopanel 18 , and the second temperature sensor 42 is installed on the second cooling stage 24 or the cryopanel unit 20 . Therefore, the first temperature sensor 40 can measure the temperature of the first-stage cryopanel 18 and output the first measured temperature signal T1 indicating the measured temperature of the first-stage cryopanel 18 . The second temperature sensor 42 can measure the temperature of the cryopanel unit 20 and output a second measured temperature signal T2 indicating the measured temperature of the cryopanel unit 20 .

The refrigerator 14 includes a refrigerator motor 50 that drives the refrigerator 14 and a refrigerator inverter 52 that controls the operating frequency of the refrigerator 14 . The operating frequency (also referred to as operating speed) of the refrigerator 14 represents the operating frequency or rotation speed of the refrigerator motor 50 , the operating frequency of the refrigerator inverter 52 , the frequency of the thermal cycle, or any of these. The frequency of thermal cycles is the number of thermal cycles performed in the refrigerator 14 per unit time.

Furthermore, the cryopump 10 is provided with a controller 60 that controls the cryopump 10 . The controller 60 may be provided integrally with the cryopump 10 , or may be configured as a separate control device from the cryopump 10 .

The controller 60 may be connected to the first temperature sensor 40 to receive the first measured temperature signal T1 from the first temperature sensor 40, and be connected to the second temperature sensor 42 to receive the first temperature signal T1 from the second temperature sensor 42. The second measured temperature signal T2 of 42. The above-mentioned refrigerator inverter 52 may be provided in the controller 60 .

The controller 60 may be configured to control the refrigerator 14 based on the cooling temperature of the first-stage cryopanel 18 or the cooling temperature of the cryopanel unit 20 during the vacuum exhaust operation of the cryopump 10 . For example, the controller 60 may control the operating frequency of the refrigerator 14 through feedback control to minimize the deviation between the target temperature of the first cooling stage 22 and the measured temperature of the first temperature sensor 40 .

The target temperature of the first cooling stage 22 is usually set to a constant value. The target temperature of the first cooling stage 22 is determined based on the process performed in the vacuum chamber 100 in which the cryopump 10 is installed, for example. When the cryopump 10 is operating, the target temperature can be changed as needed.

The controller 60 may determine the operating frequency F of the refrigerator motor 50 based on a function of the deviation between the measured temperature and the target temperature (for example, through PID control). The operating frequency F of the refrigerator motor 50 is determined within a preset operating frequency range. The operating frequency range is defined by the preset upper and lower limits of the operating frequency. The controller 60 outputs the determined operating frequency F to the refrigerator inverter 52 .

Refrigerator inverter 52 is configured to provide variable frequency control of refrigerator motor 50 . The refrigerator inverter 52 converts the input power into an operating frequency F input from the controller 60 . The input power to the refrigerator inverter 52 is supplied from a refrigerator power supply (not shown). The power supply of the freezer can be a commercial power supply. The refrigerator inverter 52 outputs the converted power to the refrigerator motor 50 . In this way, the refrigerator motor 50 is driven at the operating frequency F determined by the controller 60 and output from the refrigerator inverter 52 .

When the heat load on the cryopump 10 increases, the temperature of the first cooling stage 22 may increase. When the temperature measured by the first temperature sensor 40 is higher than the target temperature, the controller 60 increases the operating frequency of the refrigerator 14 . As a result, the frequency of the thermal cycle in the refrigerator 14 also increases, and the first-stage cryopanel 18 and the first cooling stage 22 are cooled to the target temperature. On the contrary, when the temperature measured by the first temperature sensor 40 is lower than the target temperature, the operating frequency of the refrigerator 14 is reduced and the first cooling stage 22 is heated to the target temperature. In this way, the temperature of the first-stage cryopanel 18 can be maintained within a temperature range near the target temperature. Since the operating frequency of the refrigerator 14 can be appropriately adjusted according to the heat load, such control helps to reduce the power consumption of the cryopump 10 .

In the following, controlling the refrigerator 14 so that the temperature of the first cooling stage 22 matches the target temperature may be referred to as "one-stage temperature control". In the 1st stage temperature control, the 2nd stage cooling temperature is not directly controlled. That is, as a result of the one-stage temperature control, the second cooling stage 24 and the cryopanel unit 20 are cooled to a temperature determined by the two-stage refrigeration capacity of the refrigerator 14 and the heat load on the second cooling stage 24 from the outside.

Similarly, the controller 60 can also perform so-called "two-stage temperature control" in which the refrigerator 14 is controlled so that the temperature of the second cooling stage 24 conforms to the target temperature. At this time, the controller 60 can control the operating frequency of the refrigerator 14 through feedback control to minimize the deviation between the target temperature of the second cooling stage 24 and the measured temperature of the second temperature sensor 42 . Thereby, the temperature of the cryopanel unit 20 can be made to follow the target temperature. In the 2-stage temperature control, the 1-stage cooling temperature is not directly controlled. In the two-stage temperature control, the first-stage cooling temperature is determined by the first-stage refrigeration capacity of the refrigerator 14 and the heat load on the first cooling stage 22 from the outside.

The controller 60 may be configured to control not only the cryopump 10 but also the gate valve 102 . The controller 60 may generate command signals to open and close the gate valve 102 and send them to the gate valve 102 . The gate valve 102 can receive the command signal and open or close according to the command signal. Gate valve 102 may generate gate valve signals S representing open and closed states and send them to controller 60 . The controller 60 may receive the gate valve signal S from the gate valve 102 and detect whether the gate valve 102 is closed based on the gate valve signal S.

Furthermore, the gate valve 102 may also be controlled by a controller different from the controller 60 (for example, a controller higher than the controller 60 that controls the vacuum process device). At this time, the controller 60 may receive the gate valve signal S from the controller that controls the gate valve 102 .

The internal structure of the controller 60 is realized as a hardware structure by components or circuits represented by a computer's CPU or memory, and as a software structure is realized by a computer program, etc., but is appropriately drawn as a reference in the figure. Functional blocks implemented by their collaboration. Those skilled in the art should understand that these functional blocks can be implemented in various forms through a combination of hardware and software.

For example, the controller 60 can be implemented as a combination of a processor (hardware) such as a CPU (Central Processing Unit) and a microcomputer, and a software program executed by the processor (hardware). The software program may be a computer program for causing the controller 60 to execute the operation method of the cryopump 10 .

The operation of the cryopump 10 configured as above will be described below. When the cryopump 10 is working, first use other appropriate roughing pumps to rough pump the vacuum chamber 100 to a predetermined pressure (for example, about 100 Pa or about 10 Pa). When rough evacuation of the vacuum chamber 100 is performed, the gate valve 102 is closed. Thereafter (or in parallel with rough pumping of the vacuum chamber 100) the cryopump 10 is operated. By driving the refrigerator 14, the first cooling stage 22 and the second cooling stage 24 are cooled to the first cooling temperature and the second cooling temperature respectively. Therefore, the first cryopanel unit and the second cryopanel unit thermally coupled to the thermal panels are also cooled to the first cooling temperature and the second cooling temperature respectively. The gate valve 102 is opened, and vacuum exhaust of the vacuum chamber 100 by the cryopump 10 is started.

The inlet cryopanel 32 cools the gas flying toward the cryopump 10 from the vacuum chamber. The gas whose vapor pressure is sufficiently low (for example, 10 ^{- 8} Pa or less) at the first cooling temperature condenses on the surface of the inlet cryopanel 32 . This gas can be called the first gas. The first gas is, for example, water vapor. In this way, the inlet cryopanel 32 can discharge the first gas. A part of the gas whose vapor pressure is not low enough at the first cooling temperature enters the cryopump 10 from the suction port 12 . Alternatively, another portion of the gas is reflected by the inlet cryopanel 32 and returned to the vacuum chamber 100 without entering the cryopump 10 .

The gas entering the cryopump 10 is cooled by the cryopanel unit 20 . The gas whose vapor pressure is sufficiently low (for example, 10 ^-8 Pa or less) condenses on the surface of the cryopanel unit 20 at the second cooling temperature. This gas can be called the second gas. The second gas is, for example, argon gas. In this way, the cryopanel unit 20 can discharge the second gas.

The gas whose vapor pressure is not low enough at the second cooling temperature is adsorbed on the adsorbent material of the cryopanel unit 20 . This gas can be called the third gas. The third gas is, for example, hydrogen. In this way, the cryopanel unit 20 can discharge the third gas. Therefore, the cryopump 10 can discharge various gases through condensation or adsorption, so that the vacuum degree of the vacuum chamber reaches a desired level.

By continuing the vacuum exhaust operation of the cryopump 10 , gas is accumulated in the cryopump 10 . In order to discharge the accumulated gas to the outside, the cryopump 10 is regenerated. Regeneration of the cryopump 10 generally includes a temperature increase process, a discharge process, and a cooling process. In the temperature raising step, the cryopump 10 is heated from a very low temperature for vacuum exhaust operation to a regeneration temperature (for example, room temperature). The gas captured in the cryopump 10 is vaporized. The second gas and the third gas can be easily discharged from the cryopump 10 in the temperature raising process. In the discharge process, the first gas is mainly discharged. When the discharge process is completed, the cooling process starts. In the cooling process, the cryopump 10 is cooled again to an extremely low temperature for vacuum exhaust operation. In this way, once the regeneration is completed, the cryopump 10 can start the vacuum exhaust operation again.

During regeneration of the cryopump 10, the gate valve 102 is closed. After regeneration is completed, the gate valve 102 is opened again. However, the gate valve 102 may not be opened immediately when regeneration is completed (that is, when the cooling process ends). After the regeneration is completed, the cryopump 10 can also be in a standby state in which the cryopump 10 is cooled to an extremely low temperature with the gate valve 102 closed. By opening the gate valve 102, the cryopump 10 in the standby state can immediately start evacuation of the vacuum chamber 100.

As mentioned above, by opening the gate valve 102, a large amount of gas flows from the vacuum chamber 100 into the cryopump 10 at a moment, which becomes a thermal load on the freezer 14 and may cause the cryopanel temperature to overshoot. Due to various reasons, temperature overshoot is more likely to occur on the second stage cryopanel than on the first stage cryopanel. This is purely because the temperature in the second stage is low and the temperature difference with the inflowing room temperature gas is large. In addition, in most cases, the heat capacity of the second stage is smaller than that of the first stage (large parts such as the radiation shield 30 are attached to the first stage, so the mass and thus the heat capacity are often large). The second gas, such as nitrogen, which is the main gas flowing in, does not condense on the first stage but condenses on the second stage. The latent heat generated with the phase change of the gas may increase the temperature of section 2. The temperature rise of the cryopanel may adversely affect the exhaust performance of the cryopump in some cases.

In the conventional cryopump control, when the gate valve 102 that reduces the heat load from the vacuum chamber 100 to the cryopump 10 is closed, the refrigeration capacity of the refrigerator 14 is often suppressed for energy saving. Under such control, it is effective to maintain the second stage temperature relatively high. As a result, the temperature of the second stage at the time of crossover tends to become high, and there is a concern that temperature overshoot may easily occur.

In addition, as a unique setting in the vacuum sequencer, the allowable range of the cryopanel temperature may be set in advance. If it is detected that the overshoot result exceeds the allowable temperature range, it is possible to perform actions to ensure safety by issuing an alarm or emergency closing of the gate valve 102 through the vacuum program device. The vacuum program device is on standby until the cryopanel temperature returns to the allowable range, and the start of the vacuum program is delayed accordingly.

Therefore, in this embodiment, in order to alleviate the overshoot of the cryopanel temperature that may occur during the crossover, the controller 60 is configured to detect whether the gate valve 102 is closed, and control the freezer 14 so that the freezer 14 is closed when the gate valve 102 is closed. The freezing capacity of 14 is increased compared to when the gate valve 102 is open.

FIG. 3 is a flowchart showing an example of the operating method of the cryopump 10 according to the embodiment. The controller 60 may periodically execute this process while the cryopump 10 is operating.

As shown in FIG. 3 , when starting this process, it is first determined whether the gate valve 102 is closed (S10). As an example, the controller 60 may be configured to receive a gate valve signal S indicating the open and closed status of the gate valve 102, and detect whether the gate valve 102 is closed based on the gate valve signal S. As mentioned above, the controller 60 can receive the gate valve signal S from the gate valve 102 or from other controllers.

As another method, the controller 60 may be configured to obtain the heat load on the refrigerator 14 and detect whether the gate valve 102 is closed based on the obtained heat load. The heat load on the freezer 14 mainly enters the freezer 14 from the vacuum chamber 100 through the gate valve 102 . Therefore, the thermal load on the refrigerator 14 when the gate valve 102 is closed is expected to be smaller than the thermal load on the refrigerator 14 when the gate valve 102 is open. Thus, when the thermal load on the refrigerator 14 is lower than the thermal load threshold, the gate valve 102 can be detected to be closed, and when the thermal load on the refrigerator 14 exceeds the thermal load threshold, the gate valve 102 can be detected. Open. The thermal load threshold can be obtained in advance based on the experience of the designer of the cryopump 10 or experiments or simulation experiments conducted by the designer, and can be stored in the controller 60 in advance.

The controller 60 may be configured to refer to a map representing the relationship between the heat load of the freezer 14, the operating frequency of the freezer 14, and the cryopanel temperature, and to control the operation according to the current operating frequency of the freezer 14 and the measured cryopanel temperature. to obtain the thermal load on the refrigerator 14. Such a blueprint is also called a roadmap, which can be obtained in advance based on the experience and insights of the designer of the cryopump 10 or experiments or simulation experiments conducted by the designer, and is stored in the controller 60 in advance.

For example, the first route map shows the relationship between the heat load of each of the first and second stages of the refrigerator 14, the operating frequency of the refrigerator 14 under the temperature control of the first stage, and the temperature of the second stage cryopanel. The controller 60 may refer to the first road map when executing the first stage temperature control, and obtain the first and second stages of the freezer 14 based on the current operating frequency of the freezer 14 and the measured temperature of the second stage cryogenic plate. respective heat loads. The temperature of the second stage cryopanel can be measured by the second temperature sensor 42 .

Alternatively, a second road map showing the relationship between the heat load of each of the first and second stages of the refrigerator 14, the operating frequency of the refrigerator 14 under the two-stage temperature control, and the temperature of the first-stage cryopanel may be used. The controller 60 may refer to the second road map when executing the two-stage temperature control, and obtain the first and second stages of the refrigerator 14 based on the current operating frequency of the refrigerator 14 and the measured temperature of the first-stage cryogenic plate. respective heat loads. The temperature of the first stage cryopanel can be measured by the first temperature sensor 40 .

Furthermore, the controller 60 may be configured to switch and execute 1-stage temperature control and 2-stage temperature control as needed. When the cryopump 10 performs the vacuum exhaust operation, one stage of temperature control is usually performed. The controller 60 can perform 2-stage temperature control when the cryopump 10 is in a standby state, switch from 2-stage temperature control to 1-stage temperature control at crossover, and perform 1-stage temperature control during vacuum exhaust operation. Alternatively, the controller 60 may detect whether the gate valve 102 is open, and perform 1 stage of temperature control when the gate valve 102 is open, and perform 2 stages of temperature control when the gate valve 102 is closed.

As shown in FIG. 3 , upon detecting that the gate valve 102 is closed (YES in S10 ), the controller 60 controls the refrigerator 14 so that the freezing capacity of the refrigerator 14 is increased compared to when the gate valve 102 is open ( S12 ). On the other hand, when it is detected that the gate valve 102 is opened (NO in S10), the refrigeration capacity is not increased.

As an example of control to increase the refrigeration capacity of the refrigerator 14, the controller 60 may be configured to operate the refrigerator 14 at an operating frequency equal to or higher than the first lower limit value when the gate valve 102 is open, and to operate the refrigerator 14 at an operating frequency equal to or higher than the first lower limit value when the gate valve 102 is closed. The refrigerator 14 is operated at an operating frequency equal to or higher than the second lower limit value which is greater than the first lower limit value. In this way, if the gate valve 102 is closed when the refrigerator 14 operates at an operating frequency less than the second lower limit value, the operating frequency of the refrigerator 14 will increase to the second lower limit value. If the value of the operating frequency determined by the 1-stage temperature control or the 2-stage temperature control is greater than the second lower limit value, the operating frequency of the refrigerator 14 is increased to the value. In this way, the refrigeration capacity of the refrigerator 14 when the gate valve 102 is closed can be increased compared to when the gate valve 102 is open.

Furthermore, the second lower limit value of the operating frequency may be the upper limit value of the allowable operating frequency range of the refrigerator 14 or a predetermined value slightly smaller than it (for example, it may be greater than 80% or 90% of the upper limit value). In this way, the refrigeration capacity of the refrigerator 14 when the gate valve 102 is closed can be reliably increased compared to when the gate valve 102 is open.

As another example of control to increase the freezing capacity of the refrigerator 14, the controller 60 may be configured to determine the freezing temperature so that the cooling temperature measured by the temperature sensor coincides with the first target temperature when the gate valve 102 is opened. The operating frequency of the refrigerator 14 is determined so that the cooling temperature measured by the temperature sensor coincides with the second target temperature lower than the first target temperature when the gate valve 102 is closed, and the operating frequency of the refrigerator 14 is determined. The refrigerator 14 operates at the determined operating frequency. In this manner, the refrigerator 14 can also be controlled so that the operating frequency of the refrigerator 14 when the gate valve 102 is closed is increased compared to when the gate valve 102 is open.

For example, when performing one-stage temperature control, the controller 60 may determine the operating frequency of the refrigerator 14 so that the cooling temperature measured by the first temperature sensor 40 coincides with the first target temperature when the gate valve 102 is opened. , and when the gate valve 102 is closed, the operating frequency of the refrigerator 14 is determined so that the cooling temperature measured by the first temperature sensor 40 coincides with the second target temperature which is lower than the first target temperature. At this time, the first target temperature can be selected from the range of 80K to 120K, for example. The second target temperature can be selected from a temperature of 60K or higher, for example.

Alternatively, when performing two-stage temperature control, the controller 60 may determine the operating frequency of the refrigerator 14 so that the cooling temperature measured by the second temperature sensor 42 coincides with the first target temperature when the gate valve 102 is opened. , and when the gate valve 102 is closed, the operating frequency of the refrigerator 14 is determined so that the cooling temperature measured by the second temperature sensor 42 coincides with the second target temperature which is lower than the first target temperature. At this time, the first target temperature can be selected from the range of 12K to 20K, for example. The second target temperature can be selected from the range of 10K to 12K, for example.

Furthermore, when executing the control to increase the refrigeration capacity of the refrigerator 14, the controller 60 can detect whether the gate valve 102 is opened, and end the increase in the refrigeration capacity of the refrigerator 14 if the gate valve 102 is opened. In this way, the freezing capacity of the refrigerator 14 can be restored to its original state when the gate valve 102 is opened.

FIG. 4(a) is a diagram showing the operation of the cryopump in the comparative example. As described above, in conventional cryopumps, in most cases, the heat load from the vacuum chamber to the cryopump's freezer is reduced by closing the gate valve, and therefore the freezer is controlled to suppress the freezing capability of the freezer. Therefore, as shown in Figure 4(a), while the gate valve is closed, the operating frequency of the refrigerator decreases. At this time, the heat load on the refrigerator also becomes smaller, so the cryopanel temperature (for example, the second-stage cryopanel temperature) is maintained at the target temperature Ta. However, when the gate valve opens, the situation changes. The cryopanel temperature may temporarily rise significantly due to the increased heat load on the freezer with crossover. That is, the cryopanel temperature overshoots. In this way, since the cryopanel temperature deviates from the target temperature Ta, the operating frequency of the refrigerator increases, and then the cryopanel temperature gradually returns to the target temperature Ta.

FIG. 4(b) is a diagram showing the operation of the cryopump according to the embodiment. According to the embodiment, the refrigeration capacity of the refrigerator 14 when the gate valve 102 is closed can be increased compared to when the gate valve 102 is open. As shown in Fig. 4(b), while the gate valve is closed, the operating frequency of the refrigerator 14 increases. At this time, the heat load on the refrigerator 14 becomes smaller, so the cryopanel temperature decreases. Thereafter, as the gate valve 102 opens, the heat load on the refrigerator 14 increases, and the cryopanel temperature rises. However, since the cryopanel temperature is sufficiently lowered in advance when the gate valve 102 is closed, it is expected that the cryopanel temperature will follow the target temperature Ta without greatly exceeding the target temperature Ta. In this way, according to the embodiment, an overshoot of the cryopanel temperature that may occur at the time of crossover can be mitigated.

Most of the total operation time of the cryopump 10 is the vacuum exhaust operation of the vacuum chamber 100, during which the gate valve 102 is open. The proportion of the gate valve 102 closing time in the total operating time of the cryopump 10 should be very small. Therefore, in the cryopump 10 of the embodiment, the power consumption when the gate valve 102 is closed may increase slightly, but this time is estimated to be extremely short, so it will not have a big impact.

FIG. 5 is a flowchart showing another example of the operating method of the cryopump 10 according to the embodiment. Instead of detecting the opening and closing of the gate valve 102, it may be detected whether the regeneration of the cryopump 10 is completed. Therefore, the controller 60 can detect whether the regeneration of the cryopump 10 is completed, and control the freezer 14 to temporarily increase the freezing capacity of the freezer 14 after the regeneration is completed. In this manner, as in the above embodiment, an overshoot of the cryopanel temperature that may occur at the time of crossover can be alleviated.

As shown in FIG. 5 , it is determined whether the regeneration of the cryopump 10 is completed (S20). The controller 60 may obtain the measured temperatures from the first temperature sensor 40 and the second temperature sensor 42 respectively in the regenerative cooling process, and combine the measured temperature of the first temperature sensor 40 with the temperature for the vacuum exhaust operation. The target cooling temperature of the first stage cryopanel 18 is compared, and the measured temperature of the second temperature sensor 42 is compared with the target cooling temperature of the second stage cryopanel unit 20 used for the vacuum exhaust operation. The controller 60 may continue the cooling process when any of the measured temperatures of the first temperature sensor 40 and the second temperature sensor 42 does not reach the target cooling temperature. When the measured temperatures of the second temperature sensors 42 respectively reach the target cooling temperatures, it is determined that the cooling process, that is, the regeneration of the cryopump 10 is completed.

When the regeneration of the cryopump 10 is completed (YES in S20), the controller 60 controls the refrigerator 14 to increase the refrigeration capacity of the refrigerator 14 (S22). Similar to the above embodiment, the freezing capacity of the refrigerator 14 can be increased by increasing the operating frequency of the refrigerator 14, by lowering the target temperature under the first-stage temperature control, or by increasing the target temperature under the two-stage temperature control. lower to achieve. On the other hand, if it is detected that the regeneration of the cryopump 10 has not been completed (NO in S20), the refrigeration capacity is not increased.

The control to increase the freezing capacity of the refrigerator 14 may be performed until the gate valve 102 is opened. At this time, the controller 60 may control the freezer 14 to increase the freezing capacity of the freezer 14 when the cryopump 10 is in the standby state. Alternatively, the control to increase the freezing capacity of the refrigerator 14 may be performed within a predetermined time.

FIG. 6 is a block diagram schematically showing the structure of a control device of the cryopump 10 according to another embodiment. In order to adjust the freezing capacity of the refrigerator 14, the refrigerator 14 may be equipped with a heating device 62 such as an electric heater. The heating device 62 may be provided on the first cooling stage 22 , the second cooling stage 24 , or both the first cooling stage 22 and the second cooling stage 24 . The controller 60 may be configured to switch the heating device 62 on and off and/or control the output of the heating device 62 .

The controller 60 may be configured to operate the heating device 62 with the first output when the gate valve 102 is open, and to operate the heating device 62 with a second output lower than the first output or to inactivate the heating device 62 when the gate valve 102 is closed. . By reducing the output of the heating device 62, the refrigeration capacity of the refrigerator 14 when the gate valve 102 is closed can be increased compared to when the gate valve 102 is open.

Furthermore, in the embodiment of FIG. 6 , similarly to the embodiment of FIG. 2 , the refrigerator 14 may be configured to include the refrigerator inverter 52 and to vary the operating frequency. At this time, for example, the operating frequency of the refrigerator 14 can be controlled through 1-stage temperature control or 2-stage temperature control, and the heating device 62 can be used to adjust the freezing capacity. Alternatively, in the embodiment of FIG. 6 , the refrigerator 14 may be driven at a certain operating frequency, or may not include the refrigerator inverter 52 .

The present invention has been described above based on the embodiments. Those skilled in the art will understand that the present invention is not limited to the above-described embodiments, and that various design changes and various modifications are possible, and such modifications are also within the scope of the present invention. This application claims priority based on Japanese Patent Application No. 2022-024015 filed on February 18, 2022. The entire contents of this Japanese application are incorporated by reference into this specification.

10:Cryogenic pump 14: Freezer 60:Controller 100: Vacuum chamber 102: Gate valve

[Fig. 1] is a diagram schematically showing a cryopump according to the embodiment. [Fig. 2] Fig. 2 is a block diagram schematically showing the structure of a cryopump control device according to the embodiment. [Fig. 3] is a flowchart showing an example of the operating method of the cryopump according to the embodiment. In [Fig. 4], Fig. 4(a) is a diagram showing the operation of the cryopump of the comparative example, and Fig. 4(b) is a diagram showing the operation of the cryopump of the embodiment. [Fig. 5] is a flowchart showing another example of the operating method of the cryopump according to the embodiment. 6 is a block diagram schematically showing the structure of a cryopump control device according to another embodiment.

10:Cryogenic pump

14: Freezer

40: 1st temperature sensor

42: 2nd temperature sensor

50: Freezer motor

52: Refrigerator frequency converter

60:Controller

102: Gate valve

F: operating frequency

T1: The first measured temperature signal

T2: The second measured temperature signal

S: gate valve signal

Claims (9)

A cryogenic pump that can be installed in a vacuum chamber through a gate valve and has: Freezers; and The controller is configured to detect whether the gate valve is closed and control the refrigerator so that the freezing capacity of the refrigerator when the gate valve is closed is increased compared to when the gate valve is open. The cryopump as described in claim 1, wherein, The aforementioned controller is configured to receive a gate valve signal indicating the opening and closing status of the aforementioned gate valve, and detect whether the aforementioned gate valve is closed based on the aforementioned gate valve signal. The cryopump as described in claim 1, wherein, The controller is configured to obtain the heat load on the refrigerator, and detect whether the gate valve is closed based on the obtained heat load. The cryopump as described in any one of claims 1 to 3, wherein, The aforementioned refrigeration mechanism is configured to make the operating frequency variable, The controller is configured to operate the refrigerator at an operating frequency greater than a first lower limit when the gate valve is open, and to operate the refrigerator at a second operating frequency greater than the first lower limit when the gate valve is closed. It operates at an operating frequency above the lower limit value. The cryopump as described in any one of claims 1 to 3, wherein, The aforementioned refrigeration mechanism is configured to make the operating frequency variable, The aforementioned cryopump is further equipped with a temperature sensor for measuring the cooling temperature of the aforementioned refrigerator, The controller is configured to determine the operating frequency of the refrigerator so that the cooling temperature measured by the temperature sensor coincides with the first target temperature when the gate valve is opened, and to determine the operating frequency of the refrigerator when the gate valve is closed so that the cooling temperature measured by the temperature sensor coincides with the first target temperature. The operating frequency of the refrigerator is determined so that the cooling temperature measured by the temperature sensor matches the second target temperature lower than the first target temperature, and the refrigerator is operated at the determined operating frequency. The cryopump as described in any one of claims 1 to 3, wherein, The aforementioned freezer is equipped with a heating device, The controller is configured to operate the heating device with a first output when the gate valve is open, and to operate the heating device with a second output lower than the first output when the gate valve is closed, or to inactivate the heating device. . A method of operating a cryogenic pump. The cryogenic pump can be installed in a vacuum chamber through a gate valve and equipped with a refrigerator. The aforementioned method includes the following steps: Steps to detect whether the aforementioned gate valve is closed; and A step of increasing the freezing capacity of the refrigerator when the gate valve is closed compared to when the gate valve is open. A cryogenic pump having: Freezers; and The controller detects whether the regeneration of the cryopump is completed, and controls the refrigerator to temporarily increase the freezing capacity of the refrigerator after the regeneration is completed. A method of operating a cryogenic pump. The cryogenic pump is equipped with a refrigerator. The method includes the following steps: The step of detecting whether the regeneration of the aforementioned cryogenic pump is completed; and The step of temporarily increasing the freezing capacity of the refrigerator after the aforementioned regeneration is completed.

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